This invention relates to AMS-1B crystalline molecular sieve-based catalyst systems and particularly to a method to increase activity of such catalysts.
Catalyst systems, generally useful for hydrocarbon conversion, based upon AMS-1B crystalline borosilicate molecular sieve have been described in U.S. Pat. Nos. 4,268,420, 4,269,813, 4,285,919 and Published European Application No. 68,796, all incorporated by reference herein.
As described in these references, catalyst compositions typically are formed by incorporating an AMS-1B crystalline borosilicate molecular sieve material into a matrix such as alumina, silica of silica-alumina to produce a catalyst formulation. The present invention is a method to increase activity in such compositions by treating such a formulated catalyst with an aqueous solution of a suitable ammonium compound. In one method in making AMS-1B crystalline borosilicate, sieve is formed by crystallizing sources for silicon oxide and boron oxide with sodium hydroxide and an organic compound. After crystallization, the resulting sodium form is ion exchanged with an ammonium compound and calcined to yield the hydrogen form of AMS-1B. In another method, AMS-1B crystalline borosilicate is crystallized in the hydrogen form from a mixture containing a diamine in place of a metal hydroxide. Typically, the hydrogen form sieve is gelled with an alumina sol, dried and calcined to yield a catalyst composition. The present invention is not directed to an ion exchange before catalyst formation, but is directed to post treatment of a formulated catalyst composition.